题目

Alice _____ her father that both she and her husband would be happy if he would live with them. A.convinced  B.reinforced   C.pledged  D.required 答案：A.convinced  解析: convince sb. +that从句意为“使……相信，说服……”。reinforce 加强，增强。pledge发誓，保证.如果实数x满足x2＋2x－3＝0，那么代数式的值为_______．